Hmm. I think this type of thingwould be cool if it would happen more often. Thing is you want to make the best impression possible. Going PPC is the best option. At least a Blizzard PPC board for you A1200, or an AmigaOne. Problem with this is that they cost serious cash. Also OS4 will kick OS3.9 (or below) in the face with very large shoes and put ice down its vest. Showing off doesn`t just mean putting on a slide show. They would really like to see a nice OS with lots of stuff, which looks nice and does nice stuff.....nicely. :-)
An 060 would be able to give quite a good impression, but just as long as you can pursuade the sceptics that this is FAR FAR away from the best Amiga hardware and software available, then you could still give an impression of sorts.
I know what you mean though. We do need to get mouths moving. :-)